Investigating Individual Differences in a Serial Choice Reaction Time Task: Use of Auditory Feedback and Analysis of Responses Surrounding Errors

Subjects (N = 78) performed a visual four-choice reaction time (RT) task, either with or without immediate trial-by-trial feedback, in which RT (but not accuracy) was indicated by the pitch of an auditory tone. For each feedback condition, half of the subjects (the high AH4 group) scored more than 50% on the AH4 test of fluid intelligence (Heim, 1968), whereas the remaining half (the low AH4 group) scored less than 50%. It was predicted that if low AH4 subjects were slow because they were poor at monitoring RT, they would benefit more from feedback than high AH4 subjects would. This was not supported by the data: There was some beneficial effect of feedback on RT, but only for the high AH4 group. A second possibility was that individual differences would be apparent in processes such as detecting errors and controlling RT from trial to trial. From analyses of error rates, RT distributions, and particularly sequences of responses before and after errors, there was no evidence of qualitative differences in performance between the high and low AH4 groups. It is concluded that individual differences in this task are largely determined by information-processing rate rather than by factors such as the ability to detect errors or to monitor and control RT.